An optical space communication apparatus includes a light-emitting device for emitting an elliptic light beam, and a light-projecting optical system for converting the elliptic light beam into a transmission light beam. The light-projecting optical system shapes a cross section of the transmission light beam into an elliptic shape immediately after having left the light-projecting optical system and also shapes the cross section of the transmission light beam into a nearly circular shape at a receiving point being located at the farthest distance in a transmissible distance range. <IMAGE>
